New monomer for hydrophobic acrylic copolymers and their novel properties
Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbsoch, 2006.
The synthesis and characterization of a new tertiary alcohol (2-octyl-2-dodecanol) and “bushy-tailed”, hydrophobic acrylic monomer (2-octyl-dodecyl acrylate) from a 1-decene dimer (2-octyl-1-dodecene) precursor that was synthesized with metallocene technology is reported. Some preliminary applications of the newly synthesized 2-octyl-dodecyl acrylate were investigated. These applications included the use of 2-octyl-dodecyl acrylate as a reactive hydrophobe in mini-emulsion polymerizations, and as a reactive (internal) plasticizer. In an attempt to selectively dimerize 1-decene, the effect of various factors on the oligomerization of 1-decene was investigated. These factors include the following: i. Different temperatures: 5, 35, 70 and 90°C ii. Different co-catalyst [methylaluminoxane (MAO)] concentrations iii. Different catalysts: bis(cyclopentadienyl)zirconium dichloride (Cp2ZrCl2) and bis(cyclopentadienyl)hafnium dichloride (Cp2HfCl2) iv. Different reaction times. In all instances the final product obtained, under the abovementioned conditions, was a mixture of residual monomer, the dimer and trimer of 1-decene. These findings were corroborated with GC-MS and 1H-NMR spectroscopy. The isolation and further processing of the dimer of 1-decene (2-octyl-1-dodecene) was investigated. The efficiency, in terms of the final product-composition for the amount of catalyst used and reaction time, of Cp2ZrCl2 compared to bis(cyclopentadienyl)hafnium dichloride (Cp2HfCl2; hafnocene) as catalyst for the oligomerization of 1-decene is also reported on. The results obtained indicated that Cp2ZrCl2 is the more efficient catalyst for the oligomerization of 1-decene. The effect of different reaction times (1, 3, 6, 24 hours) on the final product-composition for the oligomerization of 1-decene was also investigated. Longer reaction times (24 hours) seemed to be excessive. A reaction time of 6 hours was optimal. The purified 1-decene dimer (2-octyl-1-dodecene) was converted to the new tertiary alcohol (2-octyl-2-dodecanol) using the oxymercuration-demercuration procedure. The 2-octyl-dodecyl acrylate was synthesized by the esterification of the tertiary alcohol with acryloyl chloride in the presence of triethylamine. The new tertiary alcohol and acrylate were characterized by FT-IR and 1H-NMR spectroscopy. Stable polymer latex particles were successfully synthesized with the novel reactive hydrophobe 2-octyl-dodecyl acrylate in the mini-emulsion polymerization of butyl acrylate, methyl methacrylate and styrene. Phase-separation experiments showed that the presence of 2-octyl-dodecyl acrylate in the dispersed phase retards Ostwald ripening. The novel acrylic monomer, 2-octyl-dodecyl acrylate, was copolymerized with styrene via conventional free radical polymerization. Both low and high molecular weight copolymers were prepared. Thermal analysis of the copolymers showed that 2-octyl-dodecyl acrylate does act as a reactive (internal) plasticizer. Blends of commercial virgin polystyrene and the synthesized low and high molecular weight copolymers were prepared. Partially miscible blends were obtained. Decreases in the glass transition temperatures of the blends compared to the virgin polystyrene were observed. The higher molecular mass styrene/2-octyl-dodecyl acrylate copolymers produced larger decreases in glass-transition temperatures.